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B+W
ND filters reduce the amount of light reaching
your camera’s sensor so you need to use a
longer exposure, and whereas ND grads only
affect part of the image, solid NDs have a
uniform effect across the entire image area.
ND filters are mainly used so you can set
a slower shutter speed to record motion
in a scene or subject. The classic situation
where they’re used is on waterfalls or waves
to record the moving water as a graceful
blur, but they can be used to record motion
in any moving subject, whether natural or
man-made – commuters rushing off a train,
animals running, grass blowing in the wind,
clouds moving on a windy day and so on.
The amount of exposure increase required
depends on the density of the ND filter. A 0.3
requires a one stop increase, 0.6 two stops,
0.9 three stops, 1.2 four stops and so on.
It’s worth investing in 0.6 and 0.9NDs and
you can use them together to create a 1.5ND
which requires five stops of exposure increase.New York City, USA
For this shot taken inside Grand Central Terminal I used a 0.6ND filter
so I could set a slower shutter speed and blur the moving people.
Canon EOS 5Ds with 16-35mm zoom lens, 0.6ND, 3secs at f/16, ISO 1005 NEUTRAL DENSITY
(ND) FILTERS4 REVERSE ND GRADS
When you’re shooting landscapes at sunrise
or sunset, the brightest part of the sky is the
band just above the horizon – where the sun
is. It’s usually several stops brighter than
not only the landscape, but the sky above
it. Annoyingly, normal ND grad filters are at
their least effective close to the horizon due
to the way the ND area fades from the top of
the filter towards the centre.To overcome this, you can buy reverse
ND grads, where the ND area is at its
darkest in the centre of the filter and
graduates upwards, instead of the other
way round. I do have one or two reverse
ND grads in my filter kit, and they are
actually quite useful, but I managed for
decades with normal grads so I wouldn’t
say you need to rush out and buy any.Oia, Santorini, Greece
This is the kind of scene where a reverse ND
grad can be useful as the sky is brightest
where the sun is rising and that’s where the
ND part of the filter needs to be at its strongest.
Canon EOS 5Ds with 16-35mm zoom lens, 0.9 reverse
ND grad, 1/60sec at f/8, ISO 1005
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